Diagnosis: From all other African Garra species except of G. napata, G. sannarensis is distinguished by: its intermediate developed sucking disc, type B, vs. fully developed disc of type C in G. blanfordii, G. chebera, G. congoensis, G. ethelwynnae, G. hindii, G. ingestii, G. makiensis, G. ornata, G. quadrimaculata, G. trewavasae, G. vinciguerrae and G. jamila, and weakly developed disc of type A in G. allostoma, G. dembecha, G. dembeensis, G. duobarbis, G. regressus and G. tana; and the absence of predorsal scales vs. presence of at least some predorsal scales in G. aethiopica, G. blanfordii, G. chebera, G. congoensis, G. dembecha, G. geba, G. hindii, G. ignestii, G. lancrenonensis, G. makiensis, G. ornata, G. quadrimaculata, G. regressus, G. tana, G. trewavasae, G. waterloti and G. vinciguerrae (Ref. 122047). Garra sannarensis is distinguished from all other species of the Main Nile basin by a caudally pointed lateroposterior flap of disc vs. rounded or absent; furthermore from G. vinciguerrae by moderately sized rostral cap and densely papillated area towards mouth vs. very prominent rostral cap with fringed but smooth posterior margin, lower-lip pad quadrangular vs. round; from G. napata and G. jamila by dorsal parts of flanks continuously covered with scales vs. naked dorsolateral flanks along anterior part dorsal fin base, and further from G. napata by its slender head and inconspicuous cheeks which are not or hardly visible when viewed from above vs. broad head and visible cheeks when viewed from above (Ref. 122047). It is distinguished from G. sp. "White Nile" by its very short barbels, which do not reach the pad when bent inwards vs. barbels nearly touching each other when flexed midways (Ref. 122047).
Description: Head and anterior body region dorsoventrally slightly flattened, gradually more compressed laterally towards tail; cheeks not or hardly visible when viewed from above (Ref. 122047). Disc intermediate, type B, but with broad, papillate and triangular lateroposterior flap pointing caudally; central callus almost quadrangular; rostral cap densely covered with papillae towards mouth opening, two pairs of very short stout maxillary barbels (Ref. 122047). Dorsal fin originates midway on body, distal margin slightly convex; one minute unbranched ray perceptible only via X-ray imaging and deeply embedded into anterior dorsal fin tissue followed by one or two smaller and one large simple ray and 7 branched fin rays; pectoral fins inserting low on body; pelvic fins exceed beyond vent without reaching anal-fin base; anal fin with one or two smaller and one large simple ray and 5 branched rays; caudal fin emarginated with probably rounded upper and lower lobe (Ref. 122047). Entire body densely covered with large scales, except chest, belly and postpelvic area; area in front of dorsal fin insertion scaleless (Ref. 122047).
Colouration: Preserved specimens dark brown on flanks, dorsum and dorsal half of head; ventral third of flanks and lower half of head slightly lighter, distinct transition to pale whitish belly; scale centres light, outer rims dark and pigmented, towards tail in posterior body half forming an irregular dark reticulate pattern, pigmentation along mid lateral stripe slightly darker; vertically elongated humeral blotch exceeds beyond first lateral-line scale; caudal peduncle with dark vertical blotch and subsequent small dark stripe running through the last scale row on the base of the caudal fin rays; caudal rays conspicuously pigmented and dark, membranes in-between clear and hyaline; dorsal membrane with four spots at base of branched fin rays 3 to 6 and with distinct dark band in the middle of the membrane (Ref. 122047). Live colouration recorded only from a single juvenile: body cream-coloured, flanks with a more or less pronounced greenish band; scales on dorsal half of flank with dark outer rim causing a reticulate pattern behind the dorsal fin and on the tail; back along dorsal fin base, nape and head densely pigmented but not very dark; head and body flanks with prominent greenish iridescent, being most intense on opercles; red postopercular spot present, about half the size of the dark humeral blotch; membrane of dorsal fin hyaline; faint dark markings and base of 3rd to 5th branched dorsal ray recognisable, mid-dorsal dark band still rudimentary and hardly visible; pectoral, pelvic and anal fins hyaline, anterior margins of ventral fins and tip of dorsal fin with white margin; dark and vertically elongated blotch at end of caudal peduncle followed by a small dark stripe running through the posterior rim of last scale row on the caudal fin insertion, membranes between innermost caudal rays covered with melanophores and dark; caudal fin membrane hyaline, single melanophores along rays turn entire fin dusky; dorsal and ventral border of caudal fin slightly orange (Ref. 122047).